Turbine assembly including at least one superhard bearing

ABSTRACT

Bearing members, such as journal bearings, and turbine assemblies for use in high speed, high horsepower applications (e.g., turbochargers, jet engines, internal combustion engines, blowers, steam turbines, compressors, and pumps) including a rotatable shaft, a compressor wheel coupled to the shaft (e.g., at one end), a turbine wheel spaced from the compressor wheel, the turbine wheel also being coupled to the shaft (e.g., at another end), and at least one bearing member having a superhard bearing surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/201,220 filed on 7 Mar. 2014, which claims priority to U.S.Provisional Application No. 61/780,405 filed on 13 Mar. 2013, thedisclosure of each of which is incorporated herein, in its entirety, bythis reference.

BACKGROUND

Journal and thrust-bearing assemblies are employed in a variety of highspeed and/or high horsepower applications, such as turbochargers, jetengines, internal combustion engines, etc.

Despite the availability of a number of different bearing apparatusesfor such applications, manufacturers and users continue to seek bearingapparatuses that exhibit improved performance characteristics.

SUMMARY

Embodiments of the invention relate to turbine assemblies for use in oneor more of high horsepower, high speed, or high load engine applicationsthat include at least one superhard bearing, such as one or moresuperhard journal and/or thrust-bearing assemblies. Examples of suchengine applications include, but are not limited to turbochargers, jetengines, internal combustion engines, blowers, steam turbines,compressors, and pumps.

According to an embodiment, a turbine assembly includes a rotatableshaft, a compressor wheel coupled to the shaft (e.g., at one end), and aturbine wheel spaced from the compressor wheel and coupled to the shaft(e.g., at another end). The assembly further includes at least onebearing member (e.g., at least one thrust-bearing member or at least oneradial bearing assembly). In an embodiment, the turbine assemblyincludes at least one thrust-bearing member. In an embodiment, theturbine assembly includes at least one radial bearing member. In anotherembodiment, the turbine assembly includes at least one thrust-bearingmember and at least one radial bearing assembly.

In another embodiment, the turbine assembly includes two thrust-bearingmembers and/or two radial bearing assemblies. In another embodiment, theturbine assembly includes two thrust-bearing members and two radialbearing assemblies. The first thrust-bearing member and first radialbearing assembly may be associated with the compression wheel, while thesecond thrust-bearing and second radial bearing assembly may beassociated with the turbine wheel. For example, the first thrust-bearingmember may be disposed about the shaft (e.g., adjacent to the compressorwheel), while the second thrust-bearing member is similarly disposedabout the shaft (e.g., adjacent to the turbine wheel). Eachthrust-bearing member includes a superhard thrust-bearing surface (e.g.,polycrystalline diamond). Each radial bearing assembly is also disposedabout the shaft adjacent to a respective one of the thrust-bearingmembers. For example, the first and second thrust-bearing members may bedisposed inwardly on the shaft, between the two wheels, with the radialbearing assemblies disposed between the thrust-bearing members. Eachradial bearing assembly includes a radial bearing stator and radialbearing rotor. The rotor is coupled to the shaft, and includes a radialsuperhard bearing surface oriented generally opposed to the radialsuperhard bearing surface of the stator. The radial bearing stators mayfurther include a thrust-bearing surface (e.g., a generally planarsurface) oriented generally opposed to the thrust-bearing surface of thecorresponding thrust-bearing member. In other words, the stators mayinclude both radial and planar bearing surfaces.

Because the bearing surfaces of the thrust-bearing members and radialbearing members include a superhard material, the bearing surfaces mayprovide substantially increased wear resistance as compared toconventional materials. In an embodiment, the bearing surfaces includepolycrystalline diamond that may provide excellent wear resistance. Suchconfigurations may also provide very high thermal conductivity toquickly draw heat away from the bearing surfaces to a lubricating fluid(e.g., oil) that may be disposed about the bearing surfaces.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the invention, whereinidentical reference numerals refer to identical or similar elements orfeatures in different views or embodiments shown in the drawings.

FIG. 1 is an isometric view of an embodiment of a turbine assemblyaccording to an embodiment.

FIG. 2 is a cross-sectional view of the assembly of FIG. 1 taken alongline 2-2 thereof.

FIG. 3A is an exploded isometric view of the assembly of FIG. 1.

FIG. 3B is an exploded isometric view of another assembly according toanother embodiment.

FIG. 4A is a close-up isometric view of a thrust-bearing member of theassembly of FIG. 1.

FIG. 4B is a close-up isometric view of another embodiment of athrust-bearing member.

FIG. 5A is a close-up, exploded, isometric view of a radial bearingassembly of the assembly of FIG. 1.

FIG. 5B is a close-up, exploded, isometric view of the radial bearingassembly of FIG. 5A, but from a different angle.

FIG. 5C is a close-up, exploded, isometric view of another embodiment ofa radial bearing assembly.

FIG. 6 is a close-up, exploded, isometric view of a radial bearingassembly according to another embodiment.

FIG. 7 is a cross-sectional view of another embodiment of a turbineassembly including a thrust-bearing member.

FIG. 8 is a cross-sectional view of another embodiment of a turbineassembly including radial bearing members.

FIG. 9 is a cross-sectional view of another embodiment of a turbineassembly including combination thrust/radial bearing members.

FIG. 10 is a cross-sectional view of another embodiment of a turbineassembly including two sets of radial bearing members.

FIG. 11 is a cross-sectional view of another embodiment of a turbineassembly including combination thrust/radial bearing members.

DETAILED DESCRIPTION

Embodiments of the invention relate to turbine assemblies including atleast one superhard bearing for use in forced induction high speedengines such as turbochargers, jet engines, internal combustion engines,blowers, steam turbines, compressors, and pumps. For example, suchturbine assemblies may include one or more superhard journal andthrust-bearing assemblies. The bearing surfaces within such assembliesmay include a superhard material, such as polycrystalline diamond, whichmay provide increased wear resistance as well as may provide improvedthermal management characteristics. For example, thermal managementcharacteristics may be particularly improved where the bearing surfacesinclude diamond, which has a relatively high thermal conductivity.

The bearing surfaces may be in the form of polycrystalline diamond(“PCD”), which may be attached to a substrate to form a polycrystallinediamond compact (“PDC”). For example, in any of the embodimentsdisclosed herein the bearing surfaces that employ PCD and/or a PDC maybe formed and/or structured as disclosed in U.S. Pat. Nos. 7,516,804;7,866,418; 8,236,074; and 8,297,382; which are incorporated herein, intheir entirety, by this reference. Furthermore, in any of the bearingsurfaces that use PCD, a catalyst used to form the PCD (e.g., cobalt)may be leached to a selected depth from the bearing surface. In anembodiment, other forms of diamond may also be employed, such as naturaldiamond, other synthetic diamond, a diamond-silicon carbide composite asdisclosed in U.S. Pat. No. 7,998,573 that is incorporated herein in itsentirety by this reference, diamond deposited by chemical vapordeposition, diamond or diamond-like carbon (e.g., amorphous carbon)deposited by physical vapor deposition, or other deposition technique.

PCD includes a plurality of directly bonded-together diamond grainsexhibiting diamond-to-diamond therebetween (e.g., sp³ bonding) anddefining a plurality of interstitial regions therebetween. Typical PCDelements may be formed in a high-pressure/high-temperature (“HPHT”)process in which a volume of diamond particles is placed with ametal-solvent catalyst (e.g., typically cobalt, nickel, iron, orcombinations thereof) into a container or cartridge. The metal-solventcatalyst may be provided in the form of a metal-solventcatalyst-cemented carbide (e.g., cobalt cemented tungsten carbide)substrate to which a PCD element is to be bonded. When a substrate isemployed, the substrate and volume of diamond particles are processedunder HPHT conditions in the presence of the metal-solvent catalyst thatcauses the diamond particles to bond to one another to form a matrix ofbonded diamond grains defining a PCD element.

The cobalt or other metal-solvent catalyst (e.g., present as a cementingconstituent in the substrate) liquefies and sweeps from a regionadjacent to the volume of diamond particles into interstitial regionsbetween the diamond particles during the HPHT process. The metal-solventcatalyst acts to promote intergrowth between the diamond particles,which results in the formation of a matrix of bonded diamond grainshaving diamond-to-diamond bonding therebetween, with interstitialregions between the bonded diamond grains being occupied by themetal-solvent catalyst.

Once the PCD element is formed, the metal-solvent catalyst may beleached from at least a portion of the PCD element through exposure to asuitable acid. Even after leaching, there may remain some fraction ofresidual metal-solvent catalyst within interstitial regions of the PCDelement. Unleached PCD may also be employed.

Non-metallic catalysts can also be used in the formation of a PCDelement. For example carbonate materials, particularly alkali metaland/or alkaline earth metal carbonates, may be used to catalyze thedesired intergrowth between diamond particles. U.S. patent applicationSer. No. 12/185,457; U.S. patent application Ser. No. 13/070,636; andU.S. Pat. No. 7,635,035 disclose sintered PCD elements fabricated usingcarbonates that may be employed in any of the embodiments disclosedherein. U.S. patent application Ser. No. 12/185,457; U.S. patentapplication Ser. No. 13/070,636; and U.S. Pat. No. 7,635,035 areincorporated herein, in their entirety, by this reference. In such acase, the PCD element may include a non-metallic catalyst and/or atleast one derivative thereof disposed within at least some of theinterstitial regions of the PCD element. Most or substantially all ofany non-metallic catalyst and/or at least one derivative thereof may besubsequently removed through leaching or another suitable process.

In addition to carbonate catalysts, other non-metallic catalysts includehydroxide catalysts (e.g., alkali metal and/or alkaline earth metalhydroxides). One such suitable hydroxide may include magnesiumhydroxide. Other non-metallic catalysts that may be suitable for useinclude phosphorus, sulfur, or combinations thereof. Anothercontemplated non-traditional catalyst that may be suitable for use iscopper or copper alloys.

While diamond, particularly PCD may be particularly preferred, othersuperhard materials may also be employed for the bearing surfaces. Asused herein, a superhard material employed for the bearing surface is amaterial exhibiting a hardness that is at least as hard as tungstencarbide. Examples of superhard materials include, but are not limitedto, polycrystalline cubic boron nitride, silicon carbide, tungstencarbide, tantalum carbide, other carbides exhibiting a hardness at leastequal to that of tungsten carbide, diamond, or any combination of theforegoing. Types of diamond include, but are not limited to, naturaldiamond, polycrystalline diamond, a diamond-silicon carbide composite,diamond deposited by chemical vapor deposition, diamond or diamond-likecarbon (e.g., amorphous carbon) deposited by physical vapor deposition,or other deposition technique, or other synthetic diamond.

FIGS. 1-3A show an isometric view, a cross-sectional view, and anexploded isometric view, respectively, of an embodiment of a turbineassembly 100, which may employ diamond or other superhard bearingsurfaces therein. Assembly 100 may include a rotatable shaft 102, acompressor wheel 104, and a turbine wheel 106. Compressor wheel 104 andturbine wheel 106 may each include a plurality of blades 104′ and 106′.Although shown with one compressor wheel 104 and one turbine wheel 106,it will be understood that in an embodiment, multiple compressor and/orturbine wheels may be provided.

As shown in FIGS. 2 and 3A, first and second thrust-bearing members 108a and 108 b are disposed about shaft 102. First thrust-bearing member108 a may be disposed adjacent to compressor wheel 104, betweencompressor wheel 104 and first radial bearing assembly 110 a, whilesecond thrust-bearing member 108 b may be disposed adjacent to turbinewheel 106, between turbine wheel 106 and second radial bearing assembly110 b. FIG. 3A shows an embodiment in which holes or lubricant supplychannels are provided transversely through thrust-bearing members 108 a,108 b, inner radial race 114 a, and inner radial race 114 b. FIG. 3Bshows another embodiment, but in which the holes or lubricant supplychannels are provided through radial outer race 112 a and 112 b. FIGS.4A and 4B show close-up isometric views of a thrust-bearing member 108,as first and second thrust-bearing members 108 a and 108 b may besimilarly configured.

In addition to thrust-bearing member 108 a and 108 b disposed aboutshaft 102, assembly 100 may further include first and second radialbearing assemblies 110 a and 110 b disposed about shaft 102. Forexample, in the illustrated embodiment, compressor and turbine wheels104, 106 are disposed adjacent to opposite ends of shaft 102, withrespective thrust-bearing members 108 a and 108 b disposed adjacent toeach corresponding wheel. Respective radial bearing assemblies 110 a and110 b are shown disposed between the thrust-bearing members 108 a, 108b, with each radial bearing assembly disposed adjacent to acorresponding thrust-bearing member. FIGS. 5A and 5B show close-up viewsof a radial bearing assembly 110, as first and second radial bearingassemblies 110 a, 110 b may be differently, similarly, or identicallyconfigured.

Each radial bearing assembly 110, 110 a, 110 b may include an outerradial bearing member (e.g., a stator), also referred to as an outerrace 112, 112 a or 112 b, and an inner radial bearing member (e.g., arotor) that is also referred to as an inner race 114, 114 a, or 114 b.As radial bearing assemblies 110 a and 110 b may be similarlyconfigured, reference will be made to radial bearing assembly 110 ofFIGS. 5A and 5B. Both outer race 112 and inner race 114 include radialbearing surfaces that are oriented to be generally opposed to oneanother. For example, as shown in FIGS. 5A and 5B, where outer race 112is shaped generally as a hollow cylinder, the inside diameter of outerrace 112 may provide or at least support a radial bearing surface 116.Similarly, where inner race 114 is shaped generally as a hollowcylinder, the outside diameter of inner race 114 may provide or at leastsupport a radial bearing surface 118.

In an embodiment, the radial bearing members or races 112, 114themselves may be formed of a superhard material, such aspolycrystalline diamond, so that the entire inside diameter 116 of outerrace 112 and the entire outside diameter 118 of inner race 114 mayprovide the radial bearing surfaces. As shown in FIG. 6, in anotherembodiment, one or more bearing elements (e.g., PDCs) 120 includingbearing surfaces 116 and 118 may be mounted on outer race 112 and innerrace 114. For such a configuration, bearing surfaces 118 of elements 120mounted to inner race 114 may be convexly curved to mate with theconcave curvature of bearing surfaces 116 of elements 120 of outer race112. The inner race 114 is positioned generally within the outer race112 and, thus, the inner race 114 and outer race 112 may be configuredso that the bearing surfaces 118 and 116 may at least partially contactone another and move relative to each other as the inner race 114 andouter race 112 rotate relative to each other during use.

As shown in FIG. 4A, thrust-bearing member 108 may be shaped generallyas a hollow cylinder, and may include one or more lubricant supplychannels 109 formed therethrough, generally transverse to a longitudinalaxis A generally corresponding to shaft 102. Similarly, inner race 114may include one or more lubricant supply channels 115 formedtherethrough, generally transverse to longitudinal axis A. Duringoperation, channels 115 and 109 may allow oil or other lubricating fluidto be delivered to the bearing surfaces. In other embodiments, one ormore bearing elements in the turbine assembly may be operated withoutliquid lubricant (e.g., dry lubricated and/or air-cooled). Examples ofdry lubricants include, but are not limited to graphite, fluoropolymers(e.g., Teflon), molybdenum disulfide, hexagonal boron nitride, tungstendisulfide, and combinations thereof. In an embodiment, as describedabove in conjunction with FIG. 3B, thrust-bearing member 108 and innerrace 114 may not include channels 109 and 115, respectively, and similarchannels may be provided within outer race 112. Such a configuration isshown in FIGS. 4B and 5C.

Where both inner race 114 and thrust-bearing member 108 are attached toshaft 102 via brazing, press-fitting, or another suitable technique androtate with shaft 102, an inner planar surface 122 of thrust-bearingmember 108 may be generally oriented opposed to and in bearing contactwith a corresponding outwardly oriented planar surface 124 of outer race112. Thus, outer race 112 may include both a radial bearing surface 116(e.g., corresponding to the inside diameter of outer race 112) and aplanar bearing surface 124 oriented to bear against corresponding planarbearing surface 122 of thrust-bearing member 108.

A bearing housing 126 may also be provided for housing thrust-bearingmembers 108 a, 108 b, as well as radial bearing assemblies 110 a and 110b. Bearing housing 126 may include one or more lubricant supply channelsdisposed therethrough for supplying lubricant to the radial bearingassemblies, the thrust-bearing assemblies, or both.

By way of example, any of various PDCs or PCD tables may be employed asbearing members 108 112, or 114. For example, thrust-bearing member 108may include a generally cylindrical PCD table or PDC through which alongitudinal hole has been formed (e.g., by electro-discharge machining,laser cutting, grinding, lapping, other method, or combinations thereofto achieve the desired geometry). Inner and outer races 114 and 112 maysimilarly include PCD elements or PDCs which have been shaped into agenerally hollow cylinder. Alternatively, any of the bearing members108, 112, or 114 may include an annular support ring body that may befabricated from any suitable material, such as carbon steel, stainlesssteel, etc. over which a superhard material has been attached to providethe desired bearing surfaces. In another embodiment, one or more PDCs orPCD tables or other bodies may be mounted onto an annular support ring(e.g., as shown in FIG. 6) so that the bearing surface is provided byone or more PDCs or PCD bodies mounted on the support ring.

Outer races 112, 112 a or 112 b (or any stator) may be configured toprevent rotation of the stator. For example, the outer race or otherstator may be press-fit, keyed, may include a set screw, may be pinned,etc. relative to, for example, bearing housing 126 to prevent rotation.

Diamond has substantially higher thermal conductivity than many othersuperhard materials, such as silicon carbide and other carbides. Whereone or more of bearing surfaces 122, 124, 118, and 116 includes diamond,heat generated during operation may be better dissipated as compared toother superhard materials. Diamond provides substantially higher thermalconductivity than even conventional metal bearing materials typicallyemployed in such journal bearing assemblies. Thus, a bearing assemblyincluding superhard bearing surfaces, particularly diamond, may provideincreased wear resistance as well as better thermal managementcharacteristics.

FIGS. 7-11 show cross-sectional views of additional, generallysimplified embodiments of other turbine assemblies. For example, FIG. 7shows a turbine assembly 200, including a rotatable shaft 102, acompressor wheel 104, and a turbine wheel 106. Compressor wheel 104 andturbine wheel 106 may each include a plurality of blades 104′ and 106′.A thrust-bearing member 208 is disposed about shaft 102 and includes athrust-bearing stator surface 230. The thrust-bearing stator surface 230bears against an opposing surface 232 of compressor wheel 104 and anopposing surface of bearing housing. Such a configuration including asingle superhard thrust-bearing member may be beneficial where wear islimited to a particular component (e.g., compressor wheel 104). Whileshown disposed adjacent to compressor wheel 104, in other embodiments,it will be understood that thrust-bearing member 208 may be disposedadjacent to turbine wheel 106 or anywhere therebetween, as desired.

FIG. 8 shows another turbine assembly 300 including a rotatable shaft102, a compressor wheel 104, and a turbine wheel 106. Compressor wheel104 and turbine wheel 106 may each include a plurality of correspondingblades 104′ and 106′. A radial-bearing assembly 310 is disposed aboutshaft 102. Radial bearing assembly 310 may include an outer radialbearing member (e.g., a stator or outer race 312, and an inner radialbearing member (e.g., a rotor or inner race 314). For example, the outerrace 312 may be coupled to bearing housing 126 via bonding (e.g.,brazing or soldering), press-fitting, a mechanically connection (e.g.,one or more fasteners, by key way, threaded attachment, or combinationsthereof), or other suitable technique, and the inner race 314 may becoupled to shaft 102 by any of the same coupling techniques. While showndisposed at approximately a center point between compressor wheel 104and turbine wheel 106, in other embodiments, it will be understood thatradial-bearing assembly 310 may be disposed adjacent to turbine wheel106, adjacent to compressor wheel 104, or anywhere therebetween, asdesired.

FIG. 9 shows another turbine assembly 400 including a rotatable shaft102, a compressor wheel 104, and a turbine wheel 106. Compressor wheel104 and turbine wheel 106 may each include a plurality of correspondingblades 104′ and 106′. First and second radial-bearing assemblies 410 aand 410 b are disposed about shaft 102, with first radial bearingassembly disposed adjacent to compressor wheel 104, and second radialbearing assembly disposed adjacent to turbine wheel 106. First andsecond radial bearing assemblies 410 a and 410 b may each include anouter radial bearing member (e.g., a stator or outer race 412 a and 412b, respectively) coupled to bearing housing 126, and an inner radialbearing member (e.g., a rotor or inner race 414 a and 414 b,respectively) coupled to shaft 102. While shown with one radial bearingassembly disposed to adjacent compressor wheel 104 and the otherdisposed adjacent to turbine wheel 106, in other embodiments, it will beunderstood that radial-bearing assemblies 410 a and 410 b may bedisposed (e.g., one or more of them away from wheels 104, 106, towards acenter region between wheels 104 and 106), as desired.

FIG. 10 shows another turbine assembly 500 including a rotatable shaft102, a compressor wheel 104, and a turbine wheel 106. Compressor wheel104 and turbine wheel 106 may each include a plurality of correspondingblades 104′ and 106′. First and second combination thrust/radial-bearingassemblies 510 a and 510 b are disposed about shaft 102, with firstcombination bearing assembly 510 a disposed adjacent to compressor wheel104, and second combination bearing assembly 510 b disposed adjacent toturbine wheel 106. Each combination bearing assembly 510 a and 510 b mayinclude an inner combination bearing member (e.g., a rotor 514 a and 514b, respectively) coupled to shaft 102 and an outer combination bearingmember (e.g., a stator 512 a and 512 b, respectively) that may becoupled to bearing housing 126. Each inner bearing member 514 a, 514 bmay include a radial bearing surface (i.e., 515 a, 515 b) and athrust-bearing surface (i.e., 513 a, 513 b), which radial surfaces 515a, 515 b and thrust-bearing surfaces 513 a, 513 b are orientedsubstantially perpendicular relative to one another. Similarly, eachouter bearing member 512 a, 512 b may include a radial bearing surface(i.e., 517 a, 517 b) and a thrust-bearing surface (i.e., 511 a, 511 b).Radial bearing surfaces 517 a, 517 b are oriented to be generallyopposed to corresponding radial bearing surfaces 515 a, 515 b, whilethrust-bearing surfaces 511 a, 511 b are oriented to be opposed tocorresponding thrust-bearing rotor 513 a, 513 b. Further, as shown inFIG. 10, at least one of the stators 512 a, 512 b may include anadditional thrust-bearing surface (i.e., 530 a, 530 b) that bearsagainst an opposing surface (i.e., 532 a, 532 b) of at least one of thecompressor wheel 104 or the turbine wheel 106.

FIG. 11 shows another turbine assembly 600 including a rotatable shaft102, a compressor wheel 104, and a turbine wheel 106. Compressor wheel104 and turbine wheel 106 may each include a plurality of correspondingblades 104′ and 106′. First and second combination thrust/radial-bearingassemblies 610 a and 610 b are disposed about shaft 102, with firstcombination bearing assembly 610 a disposed adjacent to compressor wheel104, and second combination bearing assembly 610 b disposed to adjacentturbine wheel 106. Each combination bearing assembly 610 a and 610 b mayinclude an inner combination bearing member (e.g., a rotor 614 a and 614b, respectively) disposed about and coupled to shaft 102 and an outercombination bearing member (e.g., a stator 612 a and 612 b,respectively) that may be coupled to bearing housing 126. Each innerbearing member 614 a, 614 b may include an angled (e.g., from about 30°to about 60°, or about 45°) combination radial and thrust-bearingsurface (i.e., 615 a, 615 b). Each outer bearing member 612 a, 612 b mayinclude a correspondingly angled combination radial and thrust-bearingsurface (i.e., 617 a, 617 b). Combination bearing surfaces 617 a, 617 bare oriented to be generally opposed to corresponding combinationbearing surfaces 615 a, 615 b.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, shall be open ended and have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

The invention claimed is:
 1. A turbine assembly, comprising: a rotatableshaft; at least one of a compressor wheel or a turbine wheel coupled tothe shaft; a surface disposed about and coupled to the rotatable shaft,the surface extending from the rotatable shaft; a thrust-bearing rotordisposed about and coupled to the rotatable shaft, the thrust-bearingrotor spaced from the surface, the thrust-bearing rotor including athrust-bearing rotor surface extending from the rotatable shaft; and athrust-bearing stator including a first thrust-bearing stator surfaceand a second thrust-bearing stator surface, the first thrust-bearingstator surface oriented to bear against the surface in a thrust-bearingconfiguration, the second thrust-bearing stator surface oriented togenerally face the thrust-bearing rotor surface, the thrust-bearingstator defining at least one channel that extends through the statorthrust-bearing member; wherein at least the thrust-bearing statorincludes sintered polycrystalline diamond that defines the firstthrust-bearing stator surface and the second thrust-bearing statorsurface.
 2. The turbine assembly of claim 1, wherein the surfacecontacts the first thrust-bearing stator surface and the thrust-bearingrotor surface contacts the second thrust-bearing stator surface.
 3. Theturbine assembly of claim 1, wherein the surface contacts the firstthrust-bearing stator surface and the thrust-bearing rotor surface isspaced from the second thrust-bearing stator surface.
 4. The turbineassembly of claim 1, wherein sintered polycrystalline diamond definesthe surface and the thrust-bearing rotor includes sinteredpolycrystalline diamond that defines the thrust-bearing rotor surface.5. The turbine assembly of claim 4, wherein the sintered polycrystallinediamond of at least one of the surface or the thrust-bearing rotor isbonded to a cemented carbide substrate.
 6. The turbine assembly of claim1, wherein the surface and the thrust-bearing rotor exhibitssubstantially the same shape.
 7. The turbine assembly of claim 6,wherein the surface and the thrust-bearing rotor exhibits a hollowgenerally cylindrical shape.
 8. The turbine assembly of claim 1, whereinthe compressor wheel or the turbine wheel forms the surface.
 9. Theturbine assembly of claim 1, wherein surface and the secondthrust-bearing rotor are not disposed between the thrust-bearing statorand the rotatable shaft.
 10. The turbine assembly of claim 1, furthercomprising a radial bearing member disposed about the shaft, the radialbearing member including: a radial bearing stator coupled to a bearinghousing, the radial bearing stator including a radial stator superhardbearing surface; and a radial bearing rotor coupled to the rotatableshaft, the radial bearing rotor including a radial rotor superhardbearing surface oriented generally opposed to the radial statorsuperhard bearing surface of the radial bearing stator; wherein each ofthe radial bearing stator and the radial bearing rotor includes sinteredpolycrystalline diamond.
 11. The turbine assembly of claim 10, whereinat least one of: the radial bearing stator and the thrust-bearing statorare integrally formed together; or the radial bearing rotor and thesecond thrust-bearing rotor are integrally formed together.
 12. Aturbine assembly, comprising: a rotatable shaft; at least one of acompressor wheel or a turbine wheel coupled to the shaft; a bearinghousing, wherein the rotatable shaft is disposed in the bearing housing;a surface disposed about and coupled to the rotatable shaft, the surfaceextending from the rotatable shaft; a first thrust-bearing elementdisposed the rotatable shaft, the first thrust-bearing element spacedfrom the surface, the first thrust-bearing element including a firstthrust-bearing surface extending from the rotatable shaft, the firstthrust-bearing element exhibiting a hollow generally cylindrical shape;a second thrust-bearing element including a second thrust-bearingsurface oriented to generally face the surface and a thirdthrust-bearing surface oriented to generally face the firstthrust-bearing surface; wherein at least the third thrust-bearingelement includes sintered polycrystalline diamond that defines the thirdthrust-bearing surface and the fourth thrust-bearing surface.
 13. Theturbine assembly of claim 12, wherein sintered polycrystalline diamonddefines the surface and the first thrust-bearing element includessintered polycrystalline diamond that defines the first thrust-bearingsurface.
 14. The turbine assembly of claim 13, wherein the sinteredpolycrystalline diamond of at least one of the surface or the firstthrust-bearing element is bonded to a cemented carbide substrate. 15.The turbine assembly of claim 12, wherein the surface and the firstthrust-bearing element are not disposed between the secondthrust-bearing element and the rotatable shaft.
 16. The turbine assemblyof claim 12, wherein the second thrust-bearing element defines at leastone channel that extends therethrough.
 17. The turbine assembly of claim12, further comprising a radial bearing member disposed about the shaft,the radial bearing member including: a radial bearing stator coupled tothe bearing housing, the radial bearing stator including a radial statorsuperhard bearing surface; and a radial bearing rotor coupled to therotatable shaft, the radial bearing rotor including a radial statorsuperhard bearing surface oriented generally opposed to the radialstator superhard bearing surface of the radial bearing stator; whereineach of the radial bearing stator and the radial bearing rotor includessintered polycrystalline diamond, wherein the sintered polycrystallinediamond defines the radial stator superhard bearing surface and theradial stator superhard bearing surface.
 18. The turbine assembly ofclaim 17, wherein the first thrust-bearing element is integrally formedwith the radial bearing rotor.
 19. A turbine assembly, comprising: arotatable shaft extending in an axial direction; a wheel coupled to theshaft; a surface disposed about and coupled to the rotatable shaft, thesurface extending from the rotatable shaft, the surface exhibiting agenerally annular shape; a thrust-bearing rotor disposed about andcoupled to the rotatable shaft, the thrust-bearing rotor spaced from thesurface, the thrust-bearing rotor including a thrust-bearing rotorsurface extending from the rotatable shaft; a thrust-bearing statordisposed axially between the surface and the thrust-bearing rotor, thethrust-bearing stator including a first thrust-bearing stator surfaceoriented and a second thrust-bearing stator surface, the thirstthrust-bearing rotor surface oriented to bear against the surface in athrust-bearing configuration, the second thrust-bearing stator surfaceoriented to generally face the thrust-bearing rotor surface, thethrust-bearing stator defining at least one channel that extendstherethrough, wherein at least the thrust-bearing stator includessintered polycrystalline diamond that defines the first thrust-bearingstator surface and the second thrust-bearing stator surface; and aradial bearing member disposed about the shaft, the radial bearingmember including: a radial bearing stator including a radial statorsuperhard bearing surface; and a radial bearing rotor coupled to therotatable shaft, the radial bearing rotor including a radial statorsuperhard bearing surface oriented generally opposed to the radialstator superhard bearing surface of the radial bearing stator; whereineach of the radial bearing stator and the radial bearing rotor includessintered polycrystalline diamond, wherein the sintered polycrystallinediamond defines the radial stator superhard bearing surface and theradial stator superhard bearing surface.
 20. The turbine assembly ofclaim 19, wherein at least one of: the radial bearing stator and thethrust-bearing stator are integrally formed together; or the radialbearing rotor and at least one of the first thrust-bearing rotor or thesecond thrust-bearing rotor are integrally formed together.